Effect of heat treatments on the properties of hydrogenated amorphous silicon for PV and PVT applications

摘要

Photovoltaic (PV) solar cells and photovoltaic thermal (PVT) hybrid devices very often employ hydrogenated a-Si (a-Si:H) because of its cost effectiveness and better performance as light absorber. The properties of a-Si:H can be improved by heat treatments that also help to recover the Staebler Wronski effect. Here the effect of heat treatments on the behavior of H is discussed. It is shown that, upon annealing, the grown-in SiH monohydride groups are partially transformed into SiH2 dihydrides and polysilane chains which have been reported to impair the performance of a-Si:H based PV(T) devices. Since the polyhydrides reside on the surface of voids the increase of their density also affects the a-Si:H layer morphology by the formation of blisters due to the increased volume of the voids. The influence of such changes of the H bonding configuration and of the morphological structure on the performance of PV(T) devices is discussed. (C) 2015 Elsevier Ltd. All rights reserved.